Polyester/polycarbonate blends having enhanced properties

ABSTRACT

A polyester/polycarbonate (PES/PC) blend having enhanced properties as virgin material and as recyclate comprises 
     a) at least one phosphite, 
     b) at least one sterically hindered phenol, 
     c) at least one compound promoting the reaction of an epoxy resin with a PES/PC blend which is a Lewis base, and 
     d) at least one difunctional epoxy resin, with 0.01 to 10 parts of component c) being used per 100 parts of PES/PC blend.

The invention relates to polyester/polycarbonate blends having enhanced properties as well as to a process for enhancing the properties of polyester/polycarbonate blends.

Polyester/polycarbonate blends (PES/PC) such as polybutylene terephthalate/PC blends (PBT/PC) or polyethylene terephthalate/polycarbonate blends (PET/PC), or ternary blends such as PBT/PC/ABS, are important engineering plastics. These blends unite the properties of the starting polymers, such as high impact strength at room temperature and at low temperature, high rigidity, low susceptibility to stress-cracking, good resistance to chemicals, in particular to fuel, and easy coatability. Because of these properties, PBT/PC blends are preferably used for lacquered parts of large dimensions, for example in the automotive industry for the production of car bumpers. Since the production of these parts demand relatively long cycle times at elevated temperature, efficient processing stabilisation is essential.

The mechanical and physical properties of these blends furthermore depend essentially on the molecular weight of the polymer. During processing and use, however, the PES/PC blends are often damaged, resulting in reduced molecular weight. High-quality recycling of used PES/PC blends and of production waste therefore makes an increase of the molecular weight necessary.

Accordingly, it is the object of the present invention to provide PES/PC blends, more particularly PBT/PC recyclates, having enhanced properties. In this context, enhancing the properties will be taken to mean in particular enhancing the processing stability and/or increasing the molecular weight. The molecular weight increase may relate either to a single component of the blend or to both or several components of the blend simultaneously.

Surprisingly, a mixture of at least one phosphite, at least one sterically hindered phenol, at least one compound promoting the reaction of an epoxy resin with a PES/PC blend, and at least one difunctional epoxy resin, substantially enhances the properties of the blend.

Accordingly, the invention relates to a PES/PC blend comprising

a) at least one phosphite,

b) at least one sterically hindered phenol,

c) at least one compound promoting the reaction of an epoxy resin with a PES/PC blend,

and d) at least one difunctional epoxy resin, 0.01 to 10 parts of component c) being used per 100 parts of PES/PC blend.

In particular, the present invention relates to PES/PC blend recyclates, more particularly to PBT/PC or PET/PC and, very particularly, to PBT/PC recyclates. Such recyclates originate, for example, from industrial waste or useful material collections, production wastes or obligatory returnables. These recyclates may be obtained, for example, already as blend (for example in the case of car bumper materials), but may also be used as separate polymers for the preparation of the recyclate blend; e.g. PET from bottles and PC from rib-enforced sandwich panels of roof linings, or e.g. from returnable bottles. The recyclates may in particular be recyclates from car bumpers.

Furthermore, according to this invention only one component of the blend can be in the form of scrap material, for example PET bottle recyclate in combination with PC virgin material.

The polyesters may be homopolyesters or copolyesters that are derived from aliphatic, cycloaliphatic or aromatic dicarboxylic acids and diols or hydroxycarboxylic acids.

The aliphatic dicarboxylic acids may contain from 2 to 40 carbon atoms, the cycloaliphatic dicarboxylic acids from 6 to 10 carbon atoms, the aromatic dicarboxylic acids from 8 to 14 carbon atoms, the aliphatic hydroxycarboxylic acids from 2 to 12 carbon atoms, and the aromatic as well as the cycloaliphatic hydroxycarboxylic acids from 7 to 14 carbon atoms.

The aliphatic diols may contain from 2 to 12 carbon atoms, the cycloaliphatic diols from 5 to 8 carbon atoms and the aromatic diols from 6 to 16 carbon atoms.

Aromatic diols will be taken to mean those in which two hydroxyl groups are bonded to one aromatic hydrocarbon radical or to different aromatic hydrocarbon radicals.

The polyesters may also be branched with minor amounts, typically 0.1 to 3 mol %, based on the dicarboxylic acids, of more than difunctional monomers (e.g. pentaerytluitol, trimellitic acid, 1,3,5-tri(hydroxyphenyl)benzene, 2,4-dihydroxybenzoic acid or 2- (4-hydroxyphenyl)-2-(2,4-dihydroxyphenyl)propane).

If the polyesters are based on at least 2 monomers, said monomers may be randomly distributed, or they may be block copolymers.

Suitable dicarboxylic acids are linear and branched saturated aliphatic dicarboxylic acids, aromatic dicarboxylic acids and cycloaliphatic dicarboxylic acids.

Suitable aliphatic dicarboxylic acids are those containing 2 to 40 carbon atoms, typically oxalic acid, malonic acid, dimethylmalonic acid, succinic acid, pimelic acid, adipic acid, trimethyladipic acid, sebacic acid, azelaic acid and dimer acids (dimerisation products of unsaturated aliphatic carboxylic acids such as oleic acid), alkylated malonic and succinic acids such as octadecylsuccinic acid.

Suitable cycloaliphatic dicarboxylic acids are:

1,3-cyclobutanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,3- and

1,4-cyclohexanedicarboxylic acid, 1,3- and 1,4-(dicarboxylmethyl)cyclohexane,

4,4'-dicyclohexyldicarboxylic acid.

Suitable aromatic dicarboxylic acids are:

preferably terephthalic acid, isophthalic acid, o-phthalic acid, as well as 1,3-, 1,4-, 2,6- or 2,7-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenylsulfonecarboxylic acid, 4,4'-benzophenonedicarboxylic acid, 1,1,3-trimethyl-5-carboxyl-3-(p-carboxylphenyl)indane, 4,4'-diphenyl ether dicarboxylic acid, bis-p-(carboxylphenyl)methane or bis-p-(carboxylphenyl)ethane.

The aromatic dicarboxylic acids are preferred, including in particular terephthalic acid and isophthalic acid.

Further suitable dicarboxylic acids are those that contain --CO--NH-- groups and which are disclosed in DE-A 2 414 349. Dicarboxylic acids that contain N-heterocyclic rings are also suitable, for example those that are derived from carboxylalkylated, carboxylphenylated or carboxybenzylated monoamine-s-triazinedicarboxylic acids (q.v. DE-A 2 121 184 and 2 533 675), mono- or bishydantoins, benzimidazolenes or halogenated benzimidazolenes or parabanic acid. The carboxyalkyl groups may contain from 3 to 20 carbon atoms.

Suitable aliphatic diols are the linear and branched aliphatic glycols, preferably those containing 2 to 12, most preferably 2 to 6, carbon atoms in the molecule, typically including:

ethylene glycol, 1,2- and 1,3-propylene glycol, 1,2-, 1,3-, 2,3- or 1,4-butanediol, pentyl glycol, neopentyl glycol, 1,6hexanediol, 1,12-dodecanediol. A suitable cycloaliphatic diol is conveniently 1,4-dihydroxycyclohexane. Further suitable aliphatic diols are typically 1,4-bis(hydroxymethyl)cyclohexane, aromatic-aliphatic diols such as p-xylylene glycol or 2,5-dichloro-p-xylylene glycol, 2,2-(β-hydroxyethoxyphenyl)propane, as well as polyoxyalkylene glycols such as diethylene glycol, triethylene glycol, polyethylene glycol or polypropylene glycol. The alkylene diols are preferably linear and preferably contain 2 to 4 carbon atoms.

Preferred diols are the alkylene diols, 1,4-dihydroxycyclohexane and 1,4-bis(hydroxymethyl)cyclohexane. Ethylene glycol and 1,4-butanediol are especially preferred.

Further suitable aliphatic diols are the β-hydroxyalkylated, preferably β-hydroxyethylated, bisphenols such as 2,2-bis 4'-(β-hydroxyethoxy)phenyl!propane. Further bisphenols are mentioned hereinafter.

A further group of suitable aliphatic diols comprises the heterocyclic diols disclosed in German Offenlegungsschrift specifications 1 812 003, 2 342 432, 2 342 372 and 2 453 326 Illustrative examples are:

N,N'-bis(β-hydroxyethyl-5,5-dimethyl)hydantoin, N,N'-bis(β-hydroxypropyl-5,5dimethyl)hydantoin, methylenebis N-(β-hydroxyethyl)5-methyl-5-ethylhydantoin!, methylenebis N-(β-hydroxyethyl)-5,5-dimethylhydantoin!, N,N'-bis(β-hydroxyethylbenzylimidazolone, -(tetrachloro)benzimidazolone or -(tetrabromo)benzimidazolone.

Suitable aromatic diols are mononuclear diphenols and, preferably, dinuclear diphenols which carry a hydroxyl group at each aromatic nucleus. By aromatic are meant preferably aromatic hydrocarbon radicals such as phenylene or naphthylene. In addition to e.g. hydroquinone, resorcinol or 1,5-, 2,6 and 2,7-dihydroxynaphthaline, those bisphenols merit special mention that may be illustrated by the following formulae: ##STR1## The hydroxyl groups may be in m-position, but are preferably in p-position. R' and R" in this formula may be alkyl of 1 to 6 carbon atoms, halogen such as chloro or bromo and, in particular, hydrogen atoms. A may be a direct bond or O, S, SO₂, CO, P(O)(C₁ -C₂₀ alkyl), unsubstituted or substituted alkylidene, cycloalkylidene or alkylene.

Unsubstituted or substituted alkylidene is exemplified by:

ethylidene, 1,1- or 2,2-propylidene, 2,2-butylidene, 1,1-isobutylidene, pentylidene, hexylidene, heptylidene, octylidene, dichloroethylidene, trichloroethylidene.

Illustrative examples of unsubstituted or substituted alkylene are methylene, ethylene, phenylmethylene, diphenylmethylene, methylphenylmethylene. Illustrative examples of cycloalkylidene are cyclopentylidene, cyclohexylidene, cycloheptylidene and cyclooctylidene.

Illustrative examples of bisphenols are:

bis(p-hydroxyphenyl) ether or thioether, bis(p-hydroxyphenyl)sulfone, bis(p-hydroxyphenyl)methane, bis(4-hydroxyphenyl)-2,2-biphenyl, phenylhydroquinone, methylhydroquinone, trimethylhydroqinone, 1,2-bis(p-hydroxyphenyl)ethane, 1-phenyl-bis(p-hydroxyphenyl)methane, diphenyl-bis(p-hydroxyphenyl)methane, diphenyl-bis(p-hydroxyphenyl)methane, bis(3,5-dimethyl-4-hydroxyphenyl)sulfone, bis(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene, bis(3,5-dimethyl-4-hydroxyphenyl)-m-diisopropylbenzene, 2,2-bis(3',5'-dimethyl-4'-hydroxyphenyl)propane, 1,1- or 2,2-bis(p-hydroxyphenyl)butane, 2,2-bis(p-hydroxyphenyl)hexafluoropropane, 1,1-dichloro- or 1,1,1-trichloro-2,2-bis(p-hydroxyphenyl)ethane, 1,1-bis(p-hydroxyphenyl)cyclopentane and, preferably, 2,2-bis(p-hydroxyphenyl)propane (bisphenol A) and 1,1-bis(p-hydroxyphenyl)cyclohexane (bisphenol C).

Suitable polyesters of hydroxycarboxylic acids typically include polycaprolactone, polypivalolactone or the polyesters of 4-hydroxycyclohexanecarboxylic acid or 4-hydroxybenzoic acid.

Also suitable are polymers containing mainly ester bonds, but also other bonds, such as polyester amides or polyester imides.

Polyesters with aromatic dicarboxylic acids have achieved the greatest importance, in particular the polyalkylene terephthalates. Inventive moulding materials are therefore preferred in which the polyester is comprised of at least 30 mol %, preferably of at least 40 mol %, of aromatic dicarboxylic acids, and of at least 30 mol %, preferably of at least 40 mol %, of alkylenediols containing preferably 2 to 12 carbon atoms, based on the polyester.

Especially in this case the alkylenediol is linear and contains 2 to 6 carbon atoms and is exemplified by ethylene, trimethylene, tetramethylene or hexamethylene glycol and the aromatic dicarboxylic acid is terephthalic and/or isophthalic acid.

Particularly suitable polyesters are PET, PBT and corresponding copolymers.

Polycarbonate (PC) is typically obtained from bisphenol A and phosgene or a phosgene analog such as trichloromethylchloroformate, triphosgene or diphenylcarbonate, in the last mentioned case by condensation, usually by addition of a suitable transesterification catalyst, such as a boron hydride, an amine such as 2-methylimidazole or a quaternary ammonium salt. In addition to bisphenol A, other additional bisphenol components may be used, and also monomers which may be halogenated in the benzene nucleus. Particularly suitable bisphenol components that merit mention are: 2,2-bis(4'-hydroxyphenyl)propane (bisphenol A), 2,4'-dihydroxydiphenylmethane, bis(2-hydroxyphenyl)methane, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-5-propylphenyl)methane, 1,1-bis(4'-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)cyclohexylmethane, 2,2-bis(4'-hydroxyphenyl)-1phenylpropane, 2,2-bis(3',5'-dimethyl4'-hydroxyphenyl)propane, 2,2-bis(3',5'-dibromo-4'-hydroxyphenyl)propane, 2,2-bis(3',5'-dichloro-4'-hydroxyphenyl)propane, 1,1-bis(4'-hydroxyphenyl)cyclododecane, 1,1-bis(3',5'-diethyl-4'-hydroxyphenyl)cyclododecane, 1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4'-hydroxyphenyl)3,3,5,5-tetramethylcyclohexane, 1,1-bis(4'-hydroxyphenyl)-3,3,5-trimethylcyclopentane and the bisphenols indicated above. Furthermore, the polycarbonates may also be branched by suitable amounts of more than difunctional monomers (examples are as indicated above).

In addition to blends of PES and PC, i.e. in particular PBT/PC and PET/PC, suitable blends according to this invention are also ternary blends such as PBT/PC/ABS, PBT/PET/PC, PBT/PET/PC/ABS or PBT/PC/ASA blends.

The blends are prepared in customary manner from the starting polymers. The PES component is preferably PBT and the PC component is preferably a PC based on bisphenol A. The ratio of PES to PC is preferably from 95:5 to 5:95. Most preferred is a ratio in which one component constitutes at least 70%.

The transesterification reactions result in all PES/PC blends containing a lesser or greater amount of block copolymer structures, i.e. one part of the blends is in the form of a PC/PES block copolymer. The inventive enhancement of the properties increases the compatibility of the polymers with one another. However, it is also possible to increase the compatibility with so-called compatibilisers. In the present case these may typically be polyester/polycarbonate copolymers, but also polyarylates (=aromatic polyesters).

The PES/PC recyclates may also contain minor amounts of other polymers as impurities, for example polyolefins, polyurethanes, ABS or PVC. Furthermore, these recyclates may also contain standard impurities, such as dye residues, paint residues, metal traces, fuel residues and inorganic salts.

The organic phosphites which may be used as component a) in accordance with this invention are known as stabilisers for plastics. They are preferably used as processing stabilisers for polyolefins.

The phosphites to be used according to this invention are typically those of formula ##STR2## wherein

R'₁, R'₂ and R'₃ are each independently of one another alkyl of 1 to 18 carbon atoms, alkyl of 1 to 18 carbon atoms which is substituted by halogen, --COOR₄ ', --CN or --CONR_(4'R) ₄ ';

alkyl of 2 to 18 carbon atoms which is interrupted by --S--, --O-- or --NR'₄ --; cycloalkyl of 5 to 8 carbon atoms, phenyl or naphthyl; phenyl or naphthyl, each of which is substituted by halogen, 1 to 3 alkyl radicals or alkoxy radicals containing a total of 1 to 18 carbon atoms;

2,2,6,6-tetramethylpiperid-4-yl, N-allyl- or N-benzyl- or N-alkyl-2,2,6,6tetramethylpiperid-4-yl containing 1 to 4 carbon atoms in the alkyl moiety, or N-alkanoyl2,2,6,6-tetramethylpiperid-4-yl containing 1 to 4 carbon atoms in the alkyl moiety, or N-alkylene-2,2,6,6tetramethylpiperidyl or N-alkylene-4-alkoxy-2,2,6,6-tetramethylpiperidyl containing 1 to 3 carbon atoms in the alkylene moiety and 1 to 18 carbon atoms in the alkoxy moiety,

each R'₄ is independently hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, or phenylalkyl containing 1 to 4 carbon atoms in the alkyl moiety,

n' is 2, 3 or 4,

A', if n' or q=2, is alkylene of 2 to 12 carbon atoms, alkylene of 2 to 12 carbon atoms which is interrupted by --S--, --O-- or --NR'₄ --, wherein R'₄ has the given meaning, or a radical of formula ##STR3## A', if n' or q=3, is a radical of formula --C_(r) H_(2r-1) -- or N(CH₂ CH₂)₃ --, wherein

r is 5 or 6,

A', if n'=4, is the radical of formula C(CH₂)₄ --,

R₅ and R₆ are each independently of the other hydrogen or alkyl of 1 to 8 carbon atoms,

B is a radical of formula --CH₂ --, --CHR'₄ --, --CR'₁ R'₄ --, --S-- or a direct bond, wherein R'₁ and R'₄ are as indicated,

p is 1 or 2,

D', if p=1, is methyl and, if p=2, is --CH₂ OCH₂ --,

R'₉ is methyl, and R'₁₀ has the meaning of R'₁,

q is 2 or 3,

y is 1,2 or 3,

W, if y=1, is allyl of 1 to 18 carbon atoms, a radical of formula --OR'₁₆, --NR'₁₇ R'₁₈ or fluoro,

W, if y=2, is a radical of formula --O--A"--O--, or ##STR4## W, if y=3, is a radical of formula R'₄ C(CH₂ O)₃ --, N(C₂ H₄ O)₃ -- or N(C₃ H₆ O)₃ --,

wherein R'₄ has the given meaning,

R'₁₆ has the meaning of R'₁,

R'₁₇ and R'₁₈ are each independently of the other alkyl of 1 to 18 carbon atoms, benzyl, cyclohexyl, a 2,2,6,6-tetra- or 1,2,2,6,6-pentamethylpiperid-4-yl radical, or R'₁₇ and R'₁₈, taken together, are butylene, pentylene, hexylene or the radical of formula --CH₂ CH₂ --O--CH₂ CH₂ --,

A" has the meaning of A', if n'=2,

R'₁₉ is hydrogen or methyl, the substituents R'₁₄ are each independently of one another hydrogen, alkyl of 1 to 9 carbon atoms or cyclohexyl,

R'₁₅ is hydrogen or methyl, and

Z is a direct bond, --CH₂ --, --C(R'₁₄)₂ -- or --S--, wherein the substituents R'₁₄ are identical or different and have the indicated meaning.

Particularly suitable phosphites of formula (III) are those, wherein R'₁, R'₂ and R'₃ are each independently of one another alkyl of 1 to 18 carbon atoms; phenyl; phenyl which is substituted by 1 to 3 alkyl radicals containing a total of 1 to 18 carbon atoms, or 2,2,6,6tetramethylpiperid-4-yl and, more particularly, those, wherein R'₁, R'₂ and R'₃ are each independently of one another phenyl which is substituted by 1 to 3 alkyl radicals containing a total of 1 to 12 carbon atoms.

Particularly suitable phosphites of formula (IV) are those, wherein A', if n'=2, is preferably alkylene of 2 to 12 carbon atoms, --CH₂ CH₂ --O--CH₂ CH₂ --, --CH₂ CH₂ --O--CH₂ CH₂ O--CH₂ CH₂ -- or --CH₂ CH₂ --NR'₄ --CH₂ CH₂ --, or A', if n'=3, is N(CH₂ CH₂)₃ --, wherein R'₄ is alkyl of 1 to 4 carbon atoms.

Particularly suitable phosphites of formula (V) are those, wherein p is 1, D' is methyl, R'₉ is methyl and R'₁₀ is phenyl which is substituted by 1 to 3 alkyl radicals containing a total of 1 to 18 carbon atoms.

Particularly suitable phosphites of formula (VII) are those, wherein W, if y=1, is a radical of formula --OR'₁₆, --NR'₁₇ R'₁₈ or fluoro, or W, if y=2, is a radical of formula --O--CH₂ CH₂ --NR'₄ --CH₂ CH₂ --O--, or W, if y=3, is a radical of formula N(CH₂ CH₂)₃ --, wherein R'₁₆ is alkyl of 1 to 18 carbon atoms, R'₁₇ and R'₁₈ are each independently of the other alkyl of 1 to 18 carbon atoms, cyclohexyl or benzyl, or R'₁₇ and R'₁₈, taken together, form a piperidyl, morpholinyl or hexamethylene-imino radical, and R₄ has the given meaning, Z is a direct bond, --CH₂ -- or --CHCH₃ --, and the two substituents R'₁₄ are each independently of the other alkyl of 1 to 4 carbon atoms and, more particularly, W, if y=1, is 2-ethylhexyloxy or fluoro, R'₁₄ is tert-butyl, R'₁₅ is hydrogen and Z is --CH₂ -- or --CH(CH₃)--, or W, if y=2, is a radical of formula --O--CH₂ CH₂ --NCH₃ --CH₂ CH₂ --O--.

Preferred phosphites are typically trilaurylphosphite, trioctadecylphosphite, distearyl pentaerythritol diphosphite or tristearyl sorbitol triphosphite.

Aromatic phosphites are also preferred. By aromatic phosphites are meant those phosphites which contain an aromatic hydrocarbon radical such as a phenyl radical. Illustrative examples are triphenylphosphite, diphenylalkylphosphites, phenyldialkylphosphites and, specifically, tris(nonylphenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, bis(2,4-di-tertbutylphenyl)pentaerythritoldiphosphite and 2,2'-ethylidene-bis(4,6di-tert-butylphenyl)-fluorophosphite.

Of preeminent interest are phosphites containing as structural element the grouping P--O--Ar, wherein Ar is an aromatic radical, preferably an alkyl-substituted phenyl radical. Suitable alkyl substituents are C₁ -C₈ alkyl radicals or also C₅ -C₇ cycloalkyl radicals. C₁ -C₄ Alkyl radicals and, more particularly, tert-butyl (represented in the formulae by ##STR5## are preferred.

The following phosphites are particularly preferred: tris(2,4di-tert-butylphenyl)phosphite; ##STR6## The use of tris(2,4-di-tert-butylphenyl)phosphite, ##STR7## very particularly preferred.

It is preferred to use 0.01-2 parts, more particularly 0.01-1 part, of the phosphite, based on 100 parts of PES/PC blend.

The sterically hindered phenols which may be used in accordance with this invention as component b) are likewise commonly known stabilisers against the thermal-oxidative ageing of plastics, in particular of polyolefins. Typically, the sterically hindered phenols contain at least one group of formula I ##STR8## wherein R' is hydrogen, methyl or tert-butyl; and R" is unsubstituted or substituted alkyl or unsubstituted or substituted alkylthioalkyl.

A particularly suitable sterically hindered phenol is a compound of formula II, ##STR9## wherein

A is hydrogen, C₁ -C₂₄ alkyl, C₅ -C₁₂ cycloalkyl, phenyl-C₁ -C₄ alkyl, phenyl or a group --CH₂ --S--R₂₅ or ##STR10## D is C₁ -C₂₄ alkyl, C₅ -C₁₂ cycloalkyl, phenyl-C₁ -C₄ alkyl, phenyl or a group --CH₂ --S--R₂₅,

X is hydrogen, C₁ -C₁₈ alkyl or one of the groups --C_(a) H_(2a) --S_(q) --R₂₆, --C_(b) H_(2b) --CO--OR₂₇, --C_(b) H_(2b) --CO--N(R₂₉)(R₃₀), --CH₂ N(R₃₄)(R₃₅), ##STR11## R is hydrogen or a group of formula --CO--CH═CH₂, G* is hydrogen or C₁ -C₁₂ alkyl,

R₂₅ is C₁ -C₁₈ alkyl, phenyl or a group --(CH₂)_(c) --CO--OR₂₈ or --CH₂ CH₂ OR₃₃,

R₂₆ is hydrogen, C₁ -C₁₈ alkyl, phenyl, benzyl or a group ##STR12## or

--(CH₂)_(c) --CO--OR₂₈ or --CH₂ --CH₂ --OR₃₃,

R₂₇ is C₁ -C₃₀ allyl or one of the groups --CHR₃₁ --CH₂ --S--R₃₂, ##STR13## wherein Q is C₂ -C₈ alkylene,

C₄ -C₆ thiaalkylene or a group --CH₂ CH₂ (OCH₂ CH₂)_(d) --,

R₂₈ is C₁ -C₂₄ alkyl,

R₂₉ is hydrogen, C₁ -C₁₈ alkyl or cyclohexyl,

R₃₀ is C₁ -C₁₈ alkyl, cyclohexyl, phenyl; C₁ -C₁₈ alkyI-substituted phenyl, or one of the ##STR14## or R₂₉ and R₃₀, taken together, are C₄ -C₈ alkylene which may be interrupted by --O-- or --NH--,

R₃₁ is hydrogen, C₁ -C₄ alkyl or phenyl,

R₃₂ is C₁ -C₁₈ alkyl,

R₃₃ is hydrogen, C₁ -C₂₄ alkyl, phenyl, C₂ -C₁₈ alkanoyl or benzoyl,

R₃₄ is C₁ -C₁₈ alkyl, cyclohexyl, phenyl, C₁ -C₁₈ alkyl-substituted phenyl, or a group ##STR15## R₃₅ is hydrogen, C₁ -C₁₈ alkyl, cyclohexyl or a group ##STR16## R₃₄ and R₃₅, taken together, are C₄ -C₈ alkylene which may be substituted by --O-- or --NH--, a is 0, 1,2 or 3, b is 0, 1, 2 or 3, c is 1 or 2, d is 1 to 5, f is 2 to 8, and q is 1,2,3 or 4.

A preferred compound of formula II is that, wherein

A is hydrogen, C₁ -C₈ alkyl, cyclohexyl, phenyl or a group --CH₂ --S--C₁ -C₁₈ alkyl or ##STR17## D is C₁ -C₈ alkyl, cyclohexyl, phenyl or a group --CH₂ --S--C₁ -C₁₈ alkyl,

X is hydrogen, C₁ -C₈ alkyl or one of the groups --C_(a) H_(2a) --S_(q) --R₂₆, --C_(b) H_(2b) --CO--OR₂₇, --CH₂ N(R₃₄)(R₃₅), ##STR18## R₂₆ is C₁ -C₁₂ alkyl, phenyl or a group --(CH₂)_(c) --CO--OR₂₈,

R₂₇ is C₁ -C₁₈ alkyl or a group ##STR19## wherein Q is C₂ -C₈ alkylene, --CH₂ --CH₂ -S--CH₂ CH₂ or a group --CH₂ CH₂ (OCH₂ CH₂)_(d) --,

R₂₈ is C₁ -C₁₈ alkyl,

R₃₄ and R₃₅ are each independently of the other hydrogen or C₁ -C₁₂ alkyl, or

R₃₄ and R₃₅, taken together, are C₄ -C₈ alkylene which may be interrupted by --O-- or --NH--, a is 1 or 2, b is 1 or 2, c is 1 or 2, and d is 1,2 or 3.

Illustrative examples of preferred sterically hindered phenols are:

2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethylphenol, 2,6-dioctadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, 2,6-dinonyl-4-methylphenol, 2,6-di-tert-butyl-4-methoxyphenol, 2,5-ditert-butylhydroquinone, 2,5-di-tert-amyl-hydrquinone, 2,6-diphenyl-4-octadecyloxyphenol, 2,2'-thiobis(6-tert-butyl-4-methylphenol), 2,2'-thiobis(4-octylphenol), 4,4'-thiobis(6tert-butyl-3-methylphenol), 4,4'-thiobis(6-tert-butyl-2-methylphenol), 2,2'-methylenebis(6-tert-butyl-4-methylphenol), 2,2'-methylenebis(6-tert-butyl4-ethylphenol), 2,2'-methylenebis 4-methyl-6-(α-methylcyclohexyl)-phenol!, 2,2'methylenebis(4-methyl-6-cyclohexylphenol), 2,2'-methylenebis(6-nonyl-4-methylphenol), 2,2'-methylenebis(4,6di-tert-butylphenol), 2,2'-ethylidenebis(4,6-di-tert-butylphenol), 2,2'-ethylidenebis(6tert-butyl-4-isobutylphenol), 2,2'-methylenebis 6-(α-methylbenzyl)-4-nonylphenol!, 2,2'-methylenebis 6-(α,α-dimethylbenzyl)-4-nonylphenol!, 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(6-tert-butyl-2-methylphenol), 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)4-methylphenol, 1,1,3-tris(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 1,1-bis(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis 3,3-bis(3'-tert-butyl4'-hydroxyphenyl)butyrate!, bis(3-tertbutyl-4-hydroxy-5-methylphenyl)dicyclopentadiene, bis 2-(3'-tert-butyl-2'-hydroxy-5'methylbenzyl)-6tert-butyl-4-methyl-phenyl!terephthalate, 1,3,5-tris(3,5-di-tertbutyl-4-hydroxybenzyl)-2,4,6-trimethyl benzene, bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate, bis(4-tertbutyl-3-hydrox-2,6-dimethylbenzyl)dithiolterephthalate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate.

Particularly preferred sterically hindered phenols are compounds containing at least one group of formula ##STR20## wherein R' is methyl or tert-butyl; and R" is unsubstituted or substituted alkyl or unsubstituted or substituted alkylthioalkyl.

Illustrative examples of such sterically hindered phenols are: the esters of β-(3,5-ditert-butyl-4-hydroxyphenyl)propionate and of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)propionate with mono- or polyhydric alcohols, such as methanol, octanol, octadecanol, 1,6hexanediol, neopentyl glycol, thiodiethylene glycol, diethylene glycol, triethylene glycol, pentaerythritol, tris(hydroxyethyl)isocyanurate, N,N'-bis(hydroxyethyl)oxamide, as well as the amides of these acids, such as N,N'-bis(3,5-di-tert-butyl4-hydroxyphenylpropionyl)hexamethylenediamine, N,N'-bis(3,5-di-tert-butyl-4hydroxyphenylpropionyl)trimethylenediamine and N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)hydrazine.

Further particularly preferred compounds are: ##STR21## {2-(1,1-dimethylethyl)-6- 3-(1,1 -dimethylethyl)-2-hydroxy-5-methylphenyl!methyl!4-methylphenyl 2-propenoate};

{1,6-hexandiyl 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxyphenylpropanoate};

{(1,2-ethanediylbis(oxy-2,1-ethanediyl) 3-(1,1-dimethylethyl)4hydroxy-5-methylphenylpropanoate};

{2-methyl-4,6bis (octylthio)methyl!-phenol};

{2,2'-ethylidenebis(4,6di-tert-butylphenol)};

{thiodi-2,1-ethanediyl 3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropanoate};

{4,4',4"- (2,4,6-trimethyl-1,3,5-phenyltriyl)-tris(methylene)!tris 2,6-bis(1,1-dimethylethyl)phenol}; and 1,3,5-tris(3',5'-di-tert.-butyl-4'-hydroxybenzyl)-isocyanurate.

Very particularly preferred sterically hindered phenols are the pentaerytlrityl, octyl and the octadecyl ester of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid.

It is preferred to use 0.01-3 parts, more particularly 0.01-1 part, of the sterically hindered phenol, based on 100 parts of PES/PC blend.

Furthermore, it is preferred to use component a) (phosphite) and b) (sterically hindered phenol) in the ratio from 1:10 to 10:1, most preferably in the ratio from 1:4 to 4:1.

The compounds suitable for use as component c) in accordance with this invention and which promote the reaction of an epoxy resin with a PES/PC blend, belong to the group of the Lewis bases. Said compounds catalyse the reaction of an epoxy resin with a PES/PC blend Suitable compounds may be selected from the following groups:

c₁) metal oxides, metal hydroxides or metal carbonates;

c₂) metal salts of organic acids;

c₃) phosphates, phosphonates or phosphonites;

c₄) tertiary amines, quartemary ammonium salts, polyamines or polyamides;

c₅) silicates;

c₆) salts of sulfonic acids.

If component c) is an inorganic compound of the series of the metal oxides, metal hydroxides or metal carbonates, then these are preferably metal oxides, metal hydroxides or metal carbonates of the elements of the 2nd main group and 2nd, 4th and 7th auxiliary groups. Further preferred metals are calcium, magnesium, zinc, titanium and manganese, the oxides such as CaO, MgO or ZnO, as well as calcium hydroxide and calcium carbonate, being particularly preferred.

A mixture of different metal oxides, metal hydroxides or metal carbonates may also be used as component c).

If component c) is a metal salt of an organic acid, then the metal is preferably an element of the 1st main group, the 2nd main or auxiliary group, aluminium or tin.

Said metal salts are preferably zinc, magnesium, aluminium, tin or, more particularly, calcium salts of the series of the aliphatic saturated C₂ -C₂₂ carboxylates, the aliphatic olefinic C₃ -C₂₂ carboxylates, the aliphatic C₂ -C₂₂ carboxylates which are substituted by at least one OH group, the cyclic or bicyclic C₅ -C₂₂ carboxylates, the aromatic C₇ -C₂ ₂ carboxylates, the aromatic C₇ -C₂₂ carboxylates which are substituted by at least one OH group, the C₁ -C₁₆ alkyl-substituted phenylcarboxylates and the phenyl-C₁ -C₁₆ alkylcarboxylates, preferably stearates, laurates, behenates, laevulinates, lactates or thioglycolates. Examplary are also the salts of citric acid (e.g. sodium citrate), sodium benzoate or sodium naphthate.

Very particularly preferred metals soaps are calcium stearate, magnesium stearate, aluminium stearate, zinc stearate, calcium lactate or calcium laurate.

It is also possible to use a mixture of different metal soaps for component c). Component c) may typically be a mixture of calcium laurate and calcium stearate, of zinc laurate and calcium stearate or of zinc stearate and calcium stearate.

If component c) is a phosphate, phosphonate or phosphonite, then it is suitably e.g. calcium phosphate or aluminium phosphate, sodium pyrophosphate or calcium pyrophosphate, ammonium polyphosphate, triphenyl phosphate or tris(2,4-di-tert-butylphenyl)phosphate, as well as sterically hindered hydroxyphenylalkyl phosphonic acid esters or half-esters as disclosed, inter alia, in U.S. Pat. No. 4,778,840. The hydroxyphenylalkyl phosphonic acid esters or half-esters may be illustrated by the following formula: ##STR22## wherein

R₁ is isopropyl, tert-butyl, cyclohexyl or cyclohexyl which is substituted by 1 to 3 C₁ -C₄ alkyl groups;

R₂ is H, C₁ -C₄ alkyl, cyclohexyl or cyclohexyl which is substituted by 1 to 3 C₁ -C₄ alkyl groups;

R₃ is C₁ -C₂₀ alkyl, or unsubstituted or substituted phenyl or naphthyl;

R₄ is M²⁺ /2, C₁ -C₂₀ -alkyl, or unsubstituted or substituted phenyl or naphthyl;

M²⁺ is a divalent metal cation, and

n is 1 to 6.

Substituents defined as alkyl containing up to and including 8 carbon atoms are suitably radicals such as methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, stearyl or lauryl as well as the corresponding branched isomers. C₂ -C₄ Alkyl is preferred.

Suitable substituents of the phenyl or naphthyl radicals are typically C₁ -C₄ alkyl groups.

Suitable divalent metal cations are typically Zn, Ba, Ca and Mg. Calcium is particularly preferred.

Preferred compounds of formula (VIII) are those that contain at least one tert-butyl group as R₁ or R₂. Compounds in which R₁ and R₂ are tert-butyl (in the formulae: ##STR23## are very particularly preferred.

Preferably n is 1 or 2 and, most preferably, 1.

Sterically hindered hydroxyphenylalkyl phosphonic acid ester or half-ester is very particularly preferably: ##STR24## If component c) is a tertiary amine, a quarternary ammonium salt, a polyamine or a polyamide, then it is suitably trimethylbenzylammonium chloride or trimethylbenzylammonium bromide, N,N-dimethyl-4-aminopyridine, diethylaminopropylamine, tetramethylguanidine, 2-ethyl-4-methylimidazol, dimethylbenzylamine or dicyandiamide.

If component c) is a silicate, then it is suitably e.g. a dehydrotalcite such as DHT-4A®, an alcamizer or a calcium silicate hydrate (Xonotlit®).

If component c) is a salt of a sulfonic acid, then it may suitably be e.g. sodium perfluorobutanesulfonate or a p-toluene sulfonic acid salt (e.g. sodium salt).

It is also possible to use mixtures of the components c₁ to c₆.

0.01-10 parts, preferably 0.05-1 part, of component c) are used per 100 parts of PES/PC blend.

The difunctional epoxy resins which may be used as component d) according to this invention may have an aliphatic, aromatic, cycloaliphatic, alaliphatic or heterocyclic structure. They contain epoxy groups as side groups or these groups form part of an alicyclic or heterocyclic ring system. The epoxy groups are preferably linked to the residual molecule as glycidyl groups through ether or ester bonds, or they are N-glycidyl derivatives of heterocyclic amines, amides or imides. Epoxy resins of these types are commonly known and commercially available.

The epoxy resins contain two epoxy radicals, typically those of formula X ##STR25## which radicals are linked direct to carbon, oxygen, nitrogen or sulfur atoms, wherein R₁ and R₃ are both hydrogen, R₂ is hydrogen or methyl, and n=0, or wherein R₁ and R₃, taken together, are --CH₂ --CH₂ -- or --CH₂ --CH₂ --CH₂ --, in which case R₂ is hydrogen and n=0 or 1.

Illustrative examples of epoxy resins are:

I) Diglycidyl and di(β-methylglycidyl) esters which are obtainable by reacting a compound containing two carboxyl groups in the molecule and epichlorohydrin or glycerol dichlorohydrin or β-methyl epichlorohydrin. The reaction is conveniently carried out in the presence of a base.

Compounds containing two carboxyl groups in the molecule may suitably be aliphatic dicarboxylic acids. Exemplary of these dicarboxylic acids are glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid or dimerised or trimerised linoleic acid.

Cycloaliphatische dicarboxylic acids may also be used, for example tetrahydrophthalic acid, 4methyltetrahydrophthalic acid, hexahydrophthalic acid or 4-methylhexahydrophthalic acid.

Aromatic dicarboxylic acids may also be used, including phthalic acid or isophthalic acid.

II) Diglycidyl or di(β-methylglycidyl) ethers which are obtainable by reacting a compound containing two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups in the molecule with a suitably substituted epichlorohydrin under alkaline conditions or in the presence of an acid catalyst and subsequent treatment with an alkali.

Ethers of this type are typically derived from acyclic alcohols such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, 1,2-propanediol, or poly(oxypropylene) glycols, 1,3-propanediol, 1,4-butanediol, poly(oxytetramethylene) glycols, 1,5-pentanediol, 1,6hexanediol, sorbitol, as well as from polyepichlorohydrins.

They may also be derived from cycloaliphatic alcohols such as 1,3- or 1,4-dihydroxycyclohexane, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane or 1,1-bis(hydroxymethyl)cyclohex-3-ene, or they contain aromatic nuclei, such as N,N-bis(2-hydroxyethyl)aniline or p,p'-bis(2-hydroxyethylamino)diphenylmethane.

The epoxy resins may also be derived from mononuclear phenols, as from resorcinol, 1,2-benzenediol or hydroquinone, or they are based on polynuclear phenols such as 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenylsulfone, or 9,9-bis(4-hydroxyphenyl)fluorene, or on condensates of phenols with formaldehyde which are obtained under acid conditions, for example phenol novolaks.

III) Bis(N-glycidyl) compounds, obtainable typically by dehydrochlorination of the reaction products of epichlorohydrin with amines which contain two amino hydrogen atoms. These amines are typically aniline, toluidine, n-butylamine, bis(4-aminophenyl)methane, m-xylylenediamine or bis(4-methylaminophenyl)methane.

The bis(N-glycidyl) compounds, however, also include N,N'-diglycidyl derivatives of cycloalkylene ureas such as ethyleneurea or 1,3-popyleneurea, and N,N'-diglycidyl derivatives of hydantoins, typically of 5,5-dimethylhydantoin.

IV) Bis(S-glycidyl) compounds, typically bis(S-glycidyl) derivatives that are derived from dithiols such as 1,2-ethanedithiol or bis(4mercaptomethylphenyl) ether.

V) Epoxy resins containing a radical of formula X, wherein R₁ and R₃ together are --CH₂ --CH₂ -- and n is 0, typically bis(2,3-epoxycyclopentyl) ether, 2,3-epoxycyclopentylglycidyl ether or 1,2-bis(2,3-epoxycyclopentyloxy) ethane. Epoxy resins containing a radical of formula X, wherein R₁ and R₃ together are --CH₂ --CH₂ -- and n is 1, is typically 3,4-epoxy-6methylcyclohexyl-3',4'-epoxy-6'-methylcyclohexanecarboxylate.

By reason of the preparative process, the above-mentioned difunctional epoxy resins may contain minor amounts of mono- or trifunctional groups.

Furthermore, trifunctional or higher-functional epoxy resins may also be used, typically triglycidyl isocyanurate, triglycidyl trimellate or ##STR26## Diglycidyl compounds of aromatic structure are mainly used.

It is also possible to use a mixture of epoxy resins of different structure.

Particularly preferred difunctional epoxy resins are diglycidyl ethers of bisphenols, typically 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)sulfone (bisphenol S) or mixtures of bis(ortho-/para-hydroxyphenyl)methane (bisphenol F).

Epoxy resins of the diglycidyl ether of bisphenol A type (especially having a softening temperature higher than 25° C.) are very particularly preferred, e.g. Araldit® GT 6071, GT 6084, GT 7071, GT 7072, GT 6097 and GT 6099. Further compounds which are particularly preferred are, besides the diglycidyl ethers of bisphenol A, diglycidyl terephthalate, diglycidyl ether of bisphenol F, e.g. Araldit® GY 281 and PY 306, diglycidyl isophthalate, triglycidyl trimellate and ##STR27## Based on 100 parts of PES/PC blend, 0.01-5 parts, more particularly 0.02-2 parts and, most preferably, 0.05-1 part, of the difunctional epoxy resins are used.

To 100 parts of PES/PC blend are usually added 0.01 to 2 parts, preferably 0.01 to 1 part, of component a), 0.01 to 3 parts, preferably 0.01 to 1 part, of component b), 0.01 to 10 parts, preferably 0.05 to 1 part, of component c) and 0.01 to 5 parts, preferably 0.02 to 2 parts, of component d). The amount of the components a), b), c) and d) is determined in this case by the starting molecular weight of the polymer and by the desired final molecular weight, or whether a processing stability is desired.

In addition to components a), b), c) and d) further stabilisers may be added to the PES/PC blend. These further stabilisers are known to the skilled person and are selected according to the specific demands made of the end product. In particular, it is possible to add light stabilisers or also antioxidants or additional antioxidants ("Plastics Additives Handbook", Ed. R. Gachter and H. Muller, Hanser Verlag, 3rd edition, 1990; in particular pages 88/89, 92/94, 251/252 and 258/259). Likewise it is possible to add further modifiers, such as slip agents, impact strength improvers, mould release agents, fillers or reinforcing agents, such as glass fibres, flame retardants, antistatic agents and, especially for PBT/PC, modifiers that prevent transesterification during processing, for example aromatic phosphates.

1. Suitable further antioxidants are also chroman derivatives of formula ##STR28## wherein R is --(CH₂)₃ --CH(CH₃)--(CH₂)₃ --CH(CH₃)--(CH₂)₃ --CH--(CH₃)₂ or --CH₂ --CH₂ --O--C(O)--Z, and Z is C₁ -C₁₈ alkyl, --CH₂ --CH₂ --S--C₁ -C₁₈ alkyl or ##STR29## and R' or R" are hydrogen, methyl or tert-butyl, e.g. α-tocopherol, β-tocopherol, γ-tocopherol, δ-tocopherol and mixtures thereof (vitamin E).

2. UV absorbers and light stabilisers

2.1. 2-(2'-Hydroxyphenyl)benzotriazoles, for example 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-tert-butyl-2'-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole, 2-(3',5'-di-tert-butyl-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-methylphenyl)-5-chloro-benzotmazole, 2-(3'-sec-butyl-5'-tert-butyl-2'hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-4'-octyloxyphenyl)benzotriazole, 2-(3',5'di-tert-amyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-bis-(α,α-dimethylbenzyl)-2'hydroxyphenyl)benzotriazole, mixture of 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-5'- 2-(2-ethylhexyloxy)-carbonylethyl!-2'-hydroxyphenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5-(2methoxycarbonylethyl)phenyl)-5-chloro-benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-methoxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-2'-hydroxy-5'-(2-octyloxycarbonylethyl)phenyl)benzotriazole, 2-(3'-tert-butyl-5'- 2-(2-ethylhexyloxy)carbonylethyl!-2'-hydroxyphenyl)benzotriazole, 2-(3'-dodecyl-2'-hydroxy-5'-methylphenyl)benzotriazole, and 2-(3'-tert-butyl-2'-hydroxy-5'-(2-isooctyloxycarbonylethyl)phenylbenzotriazole, 2,2'-methylene-bis 4-(1,1,3,3-tetramethylbutyl)-6benzotriazole-2-ylphenol!; the transesterification product of 2- 3'-tert-butyl-5'-(2-methoxycarbonylethyl)-2'-hydroxyphenyl!-2H-benzotriazole with polyethylene glycol 300; R--CH₂ CH₂ -COO(CH₂)₃ !₂, where R=(3'-tert-butyl4'-hydroxy-5'-2H-benzotriazol-2-yl)phenyl.

2.2. 2-Hydroxybenzolhenones, for example the 4-hydroxy, 4-methoxy, 4-octyloxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4,2',4'-trihydroxy and 2'-hydroxy-4,4'-dimethoxy derivatives.

2.3. Esters of substituted and unsubstituted benzoic acids, as for example 4-tert-butylphenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoyl resorcinol, bis(4-tert-butylbenzoyl) resorcinol, benzoyl resorcinol, 2,4-di-tertbutylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl 3,5-di-tert-butyl-4-hydroxybenzoate, octadecyl 3,5-di-tertbutyl-4-thydroxybenzoate, 2-methyl-4,6di-tert-butylphenyl 3,5-di-tert-butyl-4-hydroxybenzoate.

2.4. Acrylates, for example ethyl α-cyano-β,β-diphenylacrylate, isooctyl α-cyano-β,β-diphenylacrylate, methyl α-carbomethoxycinnamate, methyl α-cyano-β-methyl-p-methoxycinnamate, butyl α-cyano-β-methyl-p-methoxy-cinnamate, methyl α-carbomethoxy-p-methoxycinnamate and N-(β-carbomethoxy-β-cyanovinyl)-2-methylindoline.

2.5. Nickel compounds, for example nickel complexes of 2,2'-thiobis 4-(1,1,3,3-tetramethylbutyl)phenol!, such as the 1:1 or 1:2 complex, with or without additional ligands such as n-butylamine, triethanolamine or N-cyclohexyldiethanolamine, nickel dibutyldithiocarbamate, nickel salts of the monoalkyl esters, e.g. the methyl or ethyl ester, of 4hydroxy-3,5-di-tert-butylbenzylphosphonic acid, nickel complexes of ketoximes, e.g. of 2-hydroxy-4-methylphenyl undecylketoxime, nickel complexes of 1 -phenyl-4-lauroyl-5-hydroxypyrazole, with or without additional ligands.

2.6. Sterically hindered amines, for example bis(2,2,6,6-tetramethyl-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-piperidyl)succinate, bis(1,2,2,6,6-pentamethylpiperidyl)sebacate, bis(1,2,2,6,6-pentamethylpiperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzylmalonate, the condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, the condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-tert-octylamino-2,6-dichloro- 1,3,5-triazine, tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane-tetracarboxylate, 1,1'-(1,2-ethanediyl)bis(3,3,5,5-tetramethylpiperazinone), 4-benzoyl-2,2,6,6tetramethylpiperidine, 4-stearyloxy-2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate, 3-n-octyl7,7,9,9-tetramethyl-1,3,8-triazasprio 4.5!decane-2,4-dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate, the condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-morpholino-2,6dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-bis(4-n-butylamino2,2,6,6-tetramethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, the condensate of 2-chloro-4,6-di(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethane, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro 4.5!decane-2,4-dione, 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidine-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethyl4-piperidyl)pyrrolidine2,5-dione.

2.7. Oxamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butoxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxanilide, 2-ethoxy-2'-ethyloxanilide, N,N'bis(3-dimethylaminopropyl)oxamide, 2-ethoxy-5-tert-butyl-2'-ethoxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxanilide and mixtures of ortho- and paramethoxy-disubstituted oxanilides and mixtures of o- and p-ethoxy-disubstituted oxanilides.

2.8. 2-(2-Hydroxyphenyl)-1,3,5-triazines, for example 2,4,6tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2-(2-hydroxy4-octyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2,4-dihydroxyphenyl)-4,6bis(2,4-diethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-propyloxyphenyl)-6(2,4-dimethylphenyl)-1,3,5-triazine, 2-(2-hydroxy4-octy 1,3,5-triazine, 2-(2-hydroxy4-dodecyloxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2- 2-hydroxy-4-(2-hydroxy3-butyloxy-propoxy)phenyl!-4,6-bis(2,4-dimethyl)-1,3,5-triazine, 2- 2-hydroxy-4-(2hydroxy-3-octyloxy-propyloxy)phenyl!-4,6-bis(2,4-dimethyl)-1,3,5-triazine.

3. Metal deactivators, for example N,N'-diphenyloxamide, N-salicylal-N'-salicyloyl hydrazine, N,N'-bis(salicyloyl) hydrazine, N,N'-bis(3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine, 3-salicyloylamino-1,2,4-triazole, bis(benzylidene)oxalyl dihydrazide, oxanilide, isophthaloyl dihydrazide, sebacoyl bisphenylhydrazide, N,N'-diacetyladipoyl dihydrazide, N,N'-bis(salicyloyl)oxalyl dihydrazide, N,N'-bis(salicyloyl)thiopropionyl dihydrazide.

4. Peroxide scavengers, for example esters of β-thiodipropionic acid, for example the lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazole or the zinc salt of 2-mercaptobenzimidazole, zinc dibutyldithiocarbamate, dioctadecyl disulfide, pentaerythritol tetrakis(β-dodecylmercapto)propionate.

5. Polyamide stabilisers, for example, copper salts in combination with iodides and/or phosphorus compounds and salts of divalent manganese.

6. Basic co-stabilisers, for example, melamine, polyvinylpyrrolidone, dicyandiamide, triallyl cyanurate, urea derivatives, hydrazine derivatives, amines, polyamides, polyurethanes.

7. Nucleating agents, for example, 4tert-butylbenzoic acid, adipic acid, diphenylacetic acid, sodium benzoate and aluminium-bis-4-(1,1-dimethylethyl)benzoatehydroxide.

8. Fillers and reinforcing agents, for example, silicates, glass fibres, talc, kaolin, mica, barium sulfate, metal oxides and hydroxides, carbon black, graphite.

9. Other additives, for example, plasticisers, lubricants, emulsifiers, pigments (such as titanium dioxide), optical brighteners, flameproofing agents, antistatic agents, blowing agents, adhesion promoters, dyes.

10. Benzofuranones and indolinones, for example those disclosed in U.S. Pat. No. 4,325,863, U.S. Pat. No. 4,338,244 or U.S. Pat. No. 5,175,312, U.S. Pat. No. 5,216,052, U.S. Pat. No. 5,252,643, DE-A-4 316 611, DE-A-4 316 622, DE-A-4 316 876, EP-A-0 589 839 or EP-A-0 591 102, or 3- 4-(2-acetoxyethoxy)phenyl!-5,7-di-tert-butyl-benzofuran-2-one, 5,7-di-tert-butyl-3- 4-(2-stearoyloxyethoxy)phenyl!benzofuran-2-one, 3,3'-bis 5,7-di-tert-butyl-3-(4- 2-hydroxyethoxy!phenyl)benzofuran-2-one!, 5,7-di-tert-butyl-3-(4-ethoxyphenyl)benzofuran-2-one, 3-(4acetoxy-3,5-dimethylphenyl)-5,7-di-tert-butyl-benzofuran-2-one, 3-(3,5-dimethyl-4-pivaloyloxyphenyl)-5,7-di-tert-butyl-benzofuran-2-one.

The preferred light stabilisers are those of the classes 2.1, 2.6 and 2.7 such as light stabilisers of the Chimassorb 944, Chimassorb 119, Tinuvin 234, Tinuvin 312, Tinuvin 622 or Tinuvin 770 type.

If the polyester/polycarbonate blend is a recyclate, then the blend can also be used in admixture with virgin material or together with virgin material, for example in a coextrusion process. These mixtures will be understood as comprising mixtures of, for example, a polyester recyclate with PC virgin material or polyester virgin material and PC recyclate, or the addition of PC virgin material or polyester virgin material to a polyester/PC recyclate blend.

Further modifiers that merit mention are the compounds usually employed for curing epoxy resins. Such modifiers include in particular: amides, amines, urea, urethanes, isocyanates, mercaptanes, alcohols, phenols, acids, acid anhydrides, silanes or silanols; typical examples thereof are: 4,4'-diaminodiphenylsulfone, dicyandiamide, N-phenyl-N-butyl-4-methylbenzenesulfonamide, 4,4'-methylenebis(phenylcyanamide), N,N'-dicyanopiperazine, toluene-2,4-diisocyanate, polyglycoldiamine, tris(mercaptoethyl)trioxane, hexahydrophthalic anhydride, pyromellitic dianhydride and trimethylchlorosilane. The addition of photoinitiators such as diazonium salts and tiriarylsulfonium salts also merits mention.

The present invention also relates to the use of a mixture comprising a) at least one phosphite, b) at least one sterically hindered phenol, c) at least one compound promoting the reaction of an epoxy resin with a PES/PC blend, and d) at least one difunctional epoxy resin, for enhancing the properties of PES/PC blends and, more particularly, of PES/PC recyclates, 0.01 to 10 parts of component c) being used per 100 parts of PES/PC blend.

The preferred embodiments of the use correspond to those of the PES/PC blend.

The invention also rate s to a process for enhancing the properties of PES/PC blends or of PES/PC recyclates, which comprises heating the PES/PC blend, with the addition of a) at least one phosphite, b) at least one sterically hindered phenol, c) at least one compound promoting the reaction of an epoxy resin with a PES/PC blend, and d) at least one difunctional epoxy resin, to above the melting point of the PES/PC blend, 0.01-10 parts of component c) being used per 100 parts of PES/PC blend. The preferred embodiments of the process correspond to those of the PES/PC blend.

The process can be carried out in any heatable container equipped with a stirrer. The process is preferably carried out in an extruder or in a kneader. It is immaterial whether processing takes place in an inert atmosphere or in the presence of oxygen.

The PES/PC blend to be heated and the components a), b), c) and d) are usually put into the apparatus when heating is started. However, a later addition is also possible, either by adding the component mixture or the individual components in any order. For this addition, the components a), b), c) and d) may be each independently of one another in the form of powder, liquid, granules or in compacted form or also on a substrate such as silica gel, or together with a polymer powder or wax, e.g. a polyethylene wax, but also in the form of a masterbatch. Heating to above the melting point is usually effected with stirring, until the components are homogenised. The temperature is governed by the PES/PC blend employed. Processing is preferably carried out in the temperature range from melting point to c. 50° C. above the melting point. A suitable temperature range for PBT/PC is typically from 220° to 300° C., preferably from 230° to 280° C. Furthermore, where there is a PET component present, processing will preferably be carried out in the upper temperature range by reason of its higher melting point.

The invention is illustrated by the following non-limitative Examples in which and in the remainder of the description, unless otherwise stated, parts and percentages are by weight.

EXAMPLES 1-2: (TABLE 1)

A PBT/PC blend (scrap material from lacquered car bumpers) is kneaded at 235° C. over a period of 15 min at 30 rpm in an oil-heated mixing chamber W 50 (Brabender) and the melt flow rate (MFR) is then determined at 250° C./2. 16 kg in accordance with ISO 1133.

EXAMPLES 3-5: (Table 2)

PBT/PC virgin material (Pocan KV 1-7916/2, sold by Bayer, DE) is kneaded at235° C. over a period of 15 min at 40 rpm in an oil-heated mixing chamber W 50 (Brabender) and the melt flow rate (MFR) is then determined at 250° C./2.16 kg in accordance with ISO 1133.

EXAMPLES 6-9: (Table 3)

A PBT/PC blend (production waste of form of a grinding stock) is kneaded at235° C. over a period of 15 min at 40 rpm in an oil-heated mixing chamber W 50 (Brabender) and the melt flow rate (MFR) is then determined at 250° C./2.16 kg in accordance with ISO 1133.

                                      TABLE 1                                      __________________________________________________________________________            Addition of                                                                               Addition of                                                                              Addition of                                                                             MFR                                              component c)                                                                              phenol and phosphite                                                                     epoxy resin                                                                              g/10 min!                                __________________________________________________________________________     Comparison 1                                                                          --         --        --       8.02                                      Example 1                                                                             0.5% Ca pyrophosphate                                                                     0.2% Irganox B 561                                                                       1% Araldit GY 281                                                                       7.35                                      Example 2                                                                             0.5% Na pyrophosphate                                                                     0.2% Irganox B 561                                                                       1% Araldit GT 6071                                                                      7.10                                      __________________________________________________________________________

                                      TABLE 2                                      __________________________________________________________________________            Addition of                                                                               Addition of                                                                              Addition of                                                                              MFR                                             component c)                                                                              phenol and phosphite                                                                     epoxy resin                                                                               g/10 min!                               __________________________________________________________________________     Comparison 2                                                                          --         --        --        4.19                                     Example 3                                                                             0.5% dicyandiamide                                                                        0.2% Irganox B 900                                                                       0.5% Araldit GT 6071                                                                     3.34                                     Example 4                                                                             0.5% sodium citrate                                                                       0.5% Irganox B 900                                                                       0.5% Araldit GT 6071                                                                     3.76                                     Example 5                                                                             0.5% sodium salt of p-                                                                    0.2% Irganox B 225                                                                       0.5% Araldit GT 6071                                                                     3.07                                            toluene sulfonic acid +                                                        0.5% Irganox 1425                                                       __________________________________________________________________________

                                      TABLE 3                                      __________________________________________________________________________            Addition of                                                                           Addition of                                                                              Addition of                                                                              MFR                                                 component c)                                                                          phenol and Phosphite                                                                     epoxy resin                                                                               g/10 min!                                   __________________________________________________________________________     Comparison 3                                                                          --     --        --        20.8                                         Example 6                                                                             1.0% Xonotlit                                                                         0.2% Irganox B 561                                                                       0.5% Araldit GT 6071                                                                     16.9                                         Example 7                                                                             1.0% Xonotlit                                                                         0.2% Irgafos 168 +                                                                       0.5% Araldit GT 6071                                                                     12.6                                                       0.2% Irganox 1330                                                Example 8                                                                             1.0% Xonotlit                                                                         0.25% Irgafos 168 +                                                                      0.25% Araldit PY 306                                                                     17.9                                                       0.25% Irganox 3114                                               Example 9                                                                             1.0% Xonotlit                                                                         0.25% Irganox 1010 +                                                                     0.25% Araldit PY 306                                                                     17.0                                                       0.25% Irgafos 12                                                 __________________________________________________________________________

The compounds used in the Examples are:

Araldit® GT 6071 (ciba; CH): diglycidyl ether of bisphenol A having an epoxy value of 2.15-2.22 eq/kg and a softening temperature from 70°to 75° C.

Araldit GY 281 (ciba; CH): liquid diglycidyl ether of bisphenol F

Araldit PY 306 (ciba; CH): diglycidyl ether of bisphenol F ##STR30##Irgafos 168 (ciba; CH): tris(2,4-di-tert-butylphenyl)phosphite Irganox®1010 (ciba; CH): pentaerythrityl ester of

β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid ##STR31##Irganox 3114 (ciba; CH): 1,3,5-tris(3',5 di-tert-butyl-4'-hydroxybenzyl)-isocyanurate

Irganox B 225 (ciba; CH): 1:1 mixture of the pentaerythrityl ester of β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and

tris(2,4-di-tert-butylphenyl)phosphite

Irganox B 561 (ciba; CH): 1:4 mixture of the pentaerythrityl ester of

β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and

tris(2,4-di-tert-butylphenyl)phosphite

Irganox B 900 (ciba; CH): 1:4 mixture of the octadecyl ester of

β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and

tris(2,4-di-tert-butylphenyl)phosphite

Xonotlit: calcium silicate hydrate 

What is claimed is:
 1. A polyester/polycarbonate blend (PES/PC blend), comprisinga) at least one phosphite, b) at least one sterically hindered phenol, c) at least one catalyst compound which is a Lewis base, and d) at least one difunctional epoxy resin, with 0.01 to 10 parts of component c) being used per 100 parts of PES/PC blend.
 2. A PES/PC blend according to claim 1, which is a PES/PC recyclate.
 3. A PES/PC blend according to claim 1, wherein component a) is a phosphite of one of the formulae ##STR32## wherein R'₁, R'₂ and R'₃ are each independently of one another alkyl of 1 to 18 carbon atoms; alkyl of 1 to 18 carbon atoms which is substituted by halogen, --COOR₄ ', --CN or --CONR₄ 'R₄ ';alkyl of 2 to 18 carbon atoms which is interrupted by --S--, --O-- or --NR'₄ --; cycloalkyl of 5 to 8 carbon atoms, phenyl or naphthyl; phenyl or naphthyl, each of which is substituted by halogen, 1 to 3 alkyl radicals or alkoxy radicals containing a total of 1 to 18 carbon atoms; 2,2,6,6-tetramethylpiperid-4yl, N-allyl- or N-benzyl- or N-alkyl-2,2,6,6tetramethylpiperid4-yl containing 1 to 4 carbon atoms in the alkyl moiety, or N-alkanoyl2,2,6,6-tetramethylpiperid-4-yl containing 1 to 4 carbon atoms in the alkyl moiety, or N-alkylene-2,2,6,6tetramethylpiperidyl or N-alkylene-4-alkoxy-2,2,6,6-tetramethylpiperidyl containing 1 to 3 carbon atoms in the alkylene moiety and 1 to 18 carbon atoms in the alkoxy moiety, each R'₄ is independently hydrogen, alkyl of 1 to 18 carbon atoms, cycloalkyl of 5 to 12 carbon atoms, or phenylalkyl containing 1 to 4 carbon atoms in the alkyl moiety, n' is 2,3 or 4, A', if n' or q=2, is alkylene of 2 to 12 carbon atoms, alkylene of 2 to 12 carbon atoms which is interrupted by --S--, --O-- or --NR'₄ --, wherein R'₄ has the given meaning, or a radical of formula ##STR33## A', if n' or q 3, is a radical of formula --C_(r) H_(2r) -- or N(CH₂ CH₂)₃ --, wherein r is 5 or 6, A', if n' =4, is the radical of formula C(CH₂)₄ --, R₅ and R₆ are each independently of the other hydrogen or alkyl of 1 to 8 carbon atoms, B is a radical of formula --CH₂ --, --CHR'₄ --, --CR'₁ R'₄ --, --S-- or a direct bond, wherein R'₁ and R'₄ are as indicated, p is 1 or 2, D', if p=1, is methyl and, if p=2, is --CH₂ OCH₂ --, R'₉ is methyl, and R'₁₀ has the meaning of R'₁, q is 2 or 3, y is 1,2 or 3, W, if y=1, is alkyl of 1 to 18 carbon atoms, a radical of formula --OR'₁₆, --NR'₁₇ R'₁₈ or fluoro, W, if y=2, is a radical of formula --O--O--A"--O--, or ##STR34## W, if y=3, is a radical of formula R'₄ C(CH₂ O)₃ --, N(C₂ H₄ O)₃ -- or N(C₃ H₆ O)₃ --, wherein R'₄ has the given meaning, R'₁₆ has the meaning of R'₁, R'₁₇ and R'₁₈ are each independently of the other alkyl of 1 to 18 carbon atoms, benzyl, cyclohexyl, a 2,2,6,6-tetra- or 1,2,2,6,6-pentamethylpiperid-4-yl radical, or R'₁₇ and R'₁₈, taken together, are butylene, pentylene, hexylene or the radical of formula --CH₂ CH₂ --O--CH₂ CH₂ --, A" has the meaning of A', if n'=2, R'₁₉ is hydrogen or methyl, the substituents R'₁₄ are each independently of one another hydrogen, alkyl of 1 to 9 carbon atoms or cyclohexyl, R'₁₅ is hydrogen or methyl, and Z is a direct bond, --CH₂ --, --C(R'₁₄)₂ -- or --S--, wherein the substituents R'₁₄ are identical or different and have the indicated meaning.
 4. A PES/PC blend according to claim 1, wherein component a) is a phosphite selected from the group consisting of tris(2,4di-tert-butylphenyl)phosphite; ##STR35##
 5. A PES/PC blend according to claim 1, wherein component b) is a sterically hindered phenol of formula II, ##STR36## wherein A is hydrogen, C₁ -C₂₄ alkyl, C₅ -C₁₂ cycloalkyl, phenyl-C₁ -C₄ alkyl, phenyl or a group --CH₂ --S--R₂₅ or ##STR37## D is C₁ -C₂₄ alkyl, C₅ -C₁₂ cycloalkyl, phenyl-C₁ -C₄ alkyl, phenyl or a group --CH₂ --S--R₂₅,X is hydrogen, C₁ -C₁₈ alkyl or one of the groups --C_(a) H_(2a) --S_(q) --R₂₆, --C_(b) H_(2b) --CO--OR₂₇, --C_(b) H_(2b) --CO--N(R₂₉)(R₃₀), --CH₂ N (R₃₄)(R₃₅), ##STR38## R is hydrogen or a group of formula --CO--CH═CH₂, G* is hydrogen or C₁ -C₁₂ alkyl, R₂₅ is C₁ -C₁₈ alkyl, phenyl or a group --(CH₂)_(c) --CO--OR₂₈ or --CH₂ CH₂ OR₃₃, R₂₆ is hydrogen, C₁ -C₁₈ alkyl, phenyl, benzyl or a group ##STR39## or --(CH₂)_(c) --CO--OR₂₈ or --CH₂ --CH₂ --OR₃₃, R₂₇ is C₁ -C₃₀ alkyl or one of the groups --CHR₃₁ --CH₂ --S--R₃₂, ##STR40## wherein Q is C₂ -C₈ alkylene, C₄ -C₆ thiaalkylene or a group --CH₂ CH₂ (OCH₂ CH₂)_(d) --, R₂₈ is C₁ -C₂₄ alky, R₂₉ is hydrogen, C₁ -C₁₈ alkyl or cyclohexyl, R₃₀ is C₁ -C₁₈ alkyl, cyclohexyl, phenyl; C₁ -C₁₈ alkyl-substituted phenyl, or one of the ##STR41## or R₂₉ and R₃₀, taken together, are C₄ -C₈ alkylene which may be interrupted by --O-- or --NH--, R₃₁ is hydrogen, C₁ -C₄ alkyl or phenyl, R₃₂ is C₁ -C₁₈ alkyl, R₃₃ is hydrogen, C₁ -C₂₄ alkyl, phenyl, C₂ -C₁₈ alkanoyl or benzoyl, R₃₄ is C₁ -C₁₈ alkyl, cyclohexyl, phenyl, C₁ -C₁₈ alkyl-substituted phenyl, or a group ##STR42## R₂₅ is hydrogen, C₁ -C₁₈ alkyl, cyclohexyl or a group ##STR43## R₃₄ and R₃₅, taken together, are C₄ -C₈ alkylene which may be substituted by --O-- or --NH--, a is 0, 1, 2 or 3, b is 0, 1, 2 or 3, c is 1 or 2, d is 1 to 5, f is 2 to 8, and q is 1,2,3 or
 4. 6. A PES/PC blend according to claim 1, wherein component c), which promotes the reaction of an epoxy resin with a PES/PC blend, is selected from one of the following groups consisting of:c₁) metal oxides, metal hydroxides or metal carbonates; c₂) metal salts of an organic acid; c₃) phosphates, phosphonates or phosphonites; c₄) tertiary amines, quarternary ammonium salts, polyamines or polyamides; c₅) silicates; and c₆) salts of sulfonic acids.
 7. A PES/PC blend according to claim 1, wherein componente d) is an epoxy resin of the diglycidyl ether of bisphenol A, diglycidyl terephthalate, diglycidyl ether of bisphenol F, diglycidyl isophthalate or triglycidyl trimellate type, or ##STR44##
 8. A PES/PC blend according to claim 1, comprising 0.01 to 2 parts of component a), 0.01 to 3 parts of component b), 0.01 to 10 parts of component c) and 0.01 to 5 parts of component d) per 100 parts of PES/PC blend.
 9. A PES/PC blend according to claim 1, comprising 0.01 to 1 part of component a), 0.01 to 1 part of component b), 0.05 to 1 part of component c) and 0.02 to 2 parts of component d) per 100 parts of PES/PC blend.
 10. A PES/PC blend according to claim 1, wherein the PES/PC blend is based on PBT/PC, PBT/PC/ABS or PBT/PC/ASA.
 11. A PES/PC blend according to claim 1, wherein the PES/PC blend is a PBT/PC blend.
 12. A process for enhancing the processing stability and/or increasing the molecular weight of PES/PC blends, which comprisesheating a PES/PC blend to above the melting point of said PES/PC blend at 220° C. to 300° C. with the addition ofa) at least one phosphite, b) at least one sterically hindered phenol, c) at least one catalyst compound which is a Lewis base, and d) at least one difunctional epoxy resin, with 0.01 to 10 parts of component c) being used per 100 parts of PES/PC blend.
 13. A PES/PC blend obtainable in accordance with the process according to claim
 12. 